AK Press Fit Barrel Info

What is the diameter of the barrel where it goes into the trunnion? Want to know to make a tool out of round stock for reverse riveting the trunnion by using a hammer instead of an expensive tool. And yes some folks have done it this way including a gun smith who wrote an article about it.

Let me add I know that the measurement is not absolute I just want a figure close to see what round stock I can get and then we will lathe it down to a friction fit. So basically I want the make a mandrel to fit where the barrel goes with a few improvements.

Also forgot the add my friend has the rivet tools/punch that you can form the round heads so appearance is not an issue.

DEPENDING ON THE TRUNION IT WILL BE 23MM FOR 7.62X39 AN IT WILL BE 22MM FOR 5.45X39 SOME 223, SAIGAS ETC,

THE ISSUE WITH BUCKING THEM ON ROD OR THE BARREL IS YOU ARE NOT REALLY SETTING THEM PROPERLY I HAVE DONE IT THAT WAY BUT ITS NOT IDEAL.

I HAVE THE OLD AGI VIDEO AN THATS HOW THEY SHOW IT BY BUCKING IT ON THE BARREL AN SPLITTING THE ENDS A LITTLT FIRST.
ITS REALLY HARD TO GET A GOOD LOOKING RIVET HED BECAUSE YOUR GOING TO BE HAMMERING ON IT . USE A TOLL WITH A DIVET IN IT IF OU GO THIS ROUTE .

YOU REALLY DONT NEED TO DO BUY A ROD JUST USE THE BARREL .

THIS IS NOT THE BEST METHOD FOR DOING THIS. AN YOU MIGHT NEED A LONGER THAN NORMAL RIVET .

The modified bolt cutter rivet crushing tool is ideal for crushing the short standard length front trunnion rivets. Offer this as an option vs the bucking trunnion insert device you are asking about..
Cost about $18-$20 for crushing tool of this type. Abut 60 minutes to fabricate., tops.

I am thinking of devising a tool that would be the round stock with a hole drilled all the way through it. Then drill a hole in the side for a rod to fit into that side hole. Then a tapered rod going through the end hole to push the side rod tight against the rivet. That rod would be bigger than the rivet head. The side rod would be short enough recess into the other larger round stock but the tapered rod would push it out and lock it in place when hammered to lock it all up tight with the wedge of the rod locking every thing up. The rivet head on the inside would be ground down flat enough to clear the barrel. Then start the rivet from the outside to get it upsetting then finish it with a rivet tool to round the head on the out side one. It should be very doable. My friend has enough money invested in the jigs he as bought so far we do not want to buy any more expensive tools. Both jigs he bought from AK builders he felt were worth buying but you got to stop somewhere or get gets cost prohibitive. I have an other friend with a shop that would make this tool I am thinking about. With the tapered rod tapped tight with a hammer it should lock up and not move.

Sounds like a lot of work when a bolt cutter mod for less that $20 will form perfect short rivets. But go for it., and post pics of your pressing tool when complete. Not sure I follow your intention but no matter.

Whats your point. Just because I am thinking of a different method of putting in rivets that has already been done but want to make a tool that makes it easier why not? As far as the bolt cutter route this tool probably is not any more work than that one is. My other friend has a mill and loves to fabricate stuff.

I used flat head rivets cut down to fit into the rivet cutouts on the trunion bore for my first build years ago before there was a bolt cutter rivet tool. I actually had to grind on a couple of the rivet heads to get clearance to push the barrel back in. Then used a rivet set and ball peen hammer to form rivet heads on the outside. With having done that, I can say (for me at least) I had less time in making the bolt cutter rivet tool and installing the rivets than the other method.

I had actually pulled the barrel and removed some of the flat headed rivets from a trunion last week that had been in there since the 90's. I was able to find what was left of 3 of them that had escaped the garbage can. You can see the curve in the head of the one on its side. Unless the heads are thin, you'll have to grind them to make them fit.